Automatically variable torque converter



Aug 18, 1942. H. F. HOBBS- AUTOMAT ICALLY VARIABLE TORQUE CONVERTOR Filed Nov. 20, 1940 4 Sheets-Sheet 2 INVENTOR H.F.HOBBS v W'W Aug. 18, 1942.

I H. F. HOBBS AUTOMATICALLY VARIABLE TORQUE CONVERTOR 4 Sheets-Sheet 5 Filed Nov. 20, 1940 INVENTOR HF HOBBS A TTYs.

1942- H. F. HOBBS 2,293,547

AUTOMATICALLY VARIABLE TORQUE CONVERTOR Filed Nov. 20, 1940 4 Sheets-Sheet 4 I500 zo'oo INVENTOR H.F Hoses ATTYS.

Patented Aug. 18, 1942 UNITED STATES PATENT OFFICE AUTOMATICALLY VARIABLE TORQUE CONVERTER Howard Frederick Hobbs, Leamington Spa, England Application November 20, 1940, Serial No. 366,465 In Great Britain November 28, 1939 Claims.

This invention relates to automatically variable torque converters, sometimes called variable torque-speed gears.

Torque converters of the fluid type as heretofore proposed can be described under two heads, viz., (a) the type in which fluid is projected against reaction and driving blades and exerts pressure on the blades as it moves past the blades at high speed; this type may be referred to as the hydro-kinetic or turbo type, examples of which are the Fottinger, Lysholm-Smith, Vickers-Coats and Leyland torque converters; and (b) the type in which fluid pressure developed by a variable displacement type pump is exerted against reaction and driving elements without depending on the velocity of the fluid relative to the driving and reaction elements but depending on direct or static pressure of the fluid on the movable parts; this type may be called the "hydro-static or fluid displacement type, and examples of this type are the Vickers swash-plate variable gear, and the Hele-Shaw gear.

The disadvantage of the kinetic type is that the shape of the blades can only be designed to give high efficiency at one speed of the movable blades and at other speeds the gear becomes ineflicient, and moreover very high fluid speeds are involved with consequential high friction and with the result that efliciency falls off rapidly over a certain ratio (for example over 3:1) and falls to zero long before top gear (1:1 transmission ratio) is reached, e. g., at about 2:1, so that this type of gear usually has a clutch for jumping to 1:1 over the inefficient ratios into direct drive. These ratios which are thus not used are however of considerable importance especially in certain applications in touring cars and kinetic gears are therefore unsuitable for such applications. Also any entry of air into this type of gear greatly reduces its efflciency.

The disadvantages of the static type are mainly the mechanical difiiculties, e. g., the knocking of the valves, the difficulty of obtaining noiseless operation of the variable pump elements, mechanical and fluid friction, and in this type also entry of air greatly reduces its efficiency.

Attempts have also been made to combine these two types, e. g., a variable pump delivering jets of fluid to a turbine.

The present invention involves the static type of fluid pressure but the pressure is produced as a centrifugal head of pressure, drive of the output shaft and reaction on to a fixed part being effected by static pressure of fluid under centrifugal action of the fluid.

The above described and other features of the invention all set forth in the appended claiming clauses will now be described by way of example with reference to the accompanying diagrammatic drawings, wherein:

Figure 1 is a sectional View of a torque converter made in accordance with the invention, the upper half of the section being taken on the radius A on Figure 2, and the lower half being taken on the radius B on Figure 2, except that.

a vertical section is shown of the housing.

Figure 2 is a sectional view on line 2-2 on Figure 1.

Figure 3 is a sectional view of the freewheel device shown in Figure 1, the section being taken on line 33 on Figure 1.

Figures 4 and 5 show types of speed and torque curves obtainable with the converter.

Figures 6 to 9 illustrate modifications in the torque converter.

Figures 10, 11 and 12 illustrate three difierent types of torque converters made in accordance with the invention.

Figures 13 and 14 illustrate a further type of torque converter made in accordance with the invention, Figure 14 being a sectional view on the line I4l4 on Figure 13.

In the torque converter illustrated in Figures 1 and 2, a rotary casing or rotor 20 formed by a cylinder closed by end plates is located within a housing I9. Bearing pins [6, H, are fixed to the end plates and rotate within the bearing bushes I5. The casing 23 is thus arranged coaxially in relation to the input shaft l8 and engine flywheel 2| and output member or shaft 22, the axis of the casing being the main or central axis of the gear. The input shaft or flywheel 21 is geared by gear wheels 24, 25, to a spindle 26 which in turn is geared to an intermediate output shaft 23 by gear wheels 21, 28. The intermediate output shaft 23 is connected through a reversing gear indicated generally at l8 to the output shaft 22. The spindle 26 is rotatably mounted in the casing 20 parallel to and offset from the main axis of the gear. The spindle 26 carries a rotary driving element or wheel 29. The casing similarly carries another spindle 30 and driving wheel 3| geared to the wheels 24, 28, the spindle 30 being offset to the spindle 26. The cas-- ing also carries two rotary spindles 32, 33, parrotary reaction element or wheels 34, 35, respectively. The spindles 32, 33, are geared by gear wheels 36 (one only of which is shownFigure 1) to a common gear wheel 43 concentric with the main axis of the gear, forces on which gear wheel can react on to a fixed member 49 (fixed to the gear housing [9) through a free wheel device 44 having rollers 50 (Figure 3).

The driving and reaction wheels have peripheral pockets formed by blades 45, 45, on the driving wheels and blades 41, 48 on the reaction wheels.

The inner peripheral wall of the casing 25 is shaped to provide two recesses 31, 38, which are separated by inwardly extending projections or dividing walls 39, 48, that are of roughly V-shape cross-section and extend inwardly between adjacent driving and reaction wheels to edges 41, 42, that are considerably nearer to the main axis of the gear than the largest diameter parts of the recesses. Adjacent to each side of each of the edges 4|, 42, the inner peripheral wall of the casing is radiused to the same curvature as the paths of movement of the outer edges of the blades 45, d6, 47, 48. The peripheral pockets in the wheels are closed at their ends by the walls of the casing and closed at their outermost parts only during part of their revolution by the radiused parts of the inner peripheral wall of the casing adjacent to the edges 4|, 42.

The vaned wheels are thus located partially within the recesses and are arranged so that the outer edges of the blades or vanes are in sliding contact with the surfaces of these recesses. The recesses each contain a reaction wheel and a driving wheel, the latter being in front of the former in relation to the driving direction if the wheels are arranged to rotate in the same direction as the casing. If, however, the wheels are so geared as to rotate in the other direction, the reaction wheel would be behind the driving wheel in relation to the driving direction.

Oilor other liquid is fed from a pump 52 into a pipe 53 having a valve 54 to open under excess pressure and a cook 55 which can be controlled from the instrument panel of a motor vehicle. The control cook 55 may, however, be connected to the accelerator pedal so that when the throttle is closed, the cock is open to its maximum extent. The oil from the pipe 53 enters a duct 56 in the shaft 22 and passes through ducts 57, 58, 59, I55, I51, into all the bearings in one of the side plates, and through duct 58, pipe I62, and ducts I63, I54, I65, into all the bearings in the other side plate. The oil from the bearings then enters the interior of the casing 26. When the gear is in operation, the casing 20 rotates and the oil therein is held centrifugally against the inner peripheral wall of the casing to form a band of fluid having a depth controlled by a small leak opening to, and by a large leak opening 6i, as well as by the cock 55. The opening Ell provides a continuous leak whilst the opening 6| prevents the depth of the band of fiuid from exceeding a predetermined maximum. The oil escapes through the openings 60, 6|, into a chamber I75 from which it can escape past a ball valve ill when the latter is open into the housing l9 from which it is drawn off by the pump 52. The ball valve Ill opens automatically by centrifugal action as soon as the casing rotates above a speed suflicient to maintain the fluid in the form of a band on its periphery.

The driving and reaction wheels are provided with openings drilled in such a direction that any oil within these wheels can escape centrifugally to the outside of the wheels and air can escape into the interior of the wheels.

When the gear is put into operation, the gear wheel 24 drives the wheels 25 and consequently the gear wheels 21 also which latter therefore revolve around the initially stationary wheel 28 thereby causing rotation of the casing 20. The oil is impelled away from the centre oithe casing by centrifugal action and is held centrifugally against the inner wall of the casing 26. Oil is carried around in the peripheral pockets of the driving wheels and becomes trapped between the peripheral pockets of the driving wheels and the adjacent sides of the projections concentric to the driving wheels. The oil is drawn inwardly of the casing against the centrifugal force on the liquid. Whilst being drawn inwardly the oil transmits torque to the driving wheels by a static or direct centrifugal head of pressure independently of any motion of the oil in relation to the blades and the torque is imparted to the output shaft through the gear wheel 28. As the wheel 28 gains in speed, the speed of rotation of the wheels 21 and consequently of the casing 20 also decreases and finally the wheels 21 cease to rotate, the casing 20 then rotating at the same. speed as the gears 24, 28. The oil is drawn inwardly to each apex or edge 4 I, 42 at which positions the oil is released and then by centrifugal action moves outwardly towards the nearest pockets of the reaction wheels and accelerates so as to reach a speed approximately equal to the speed of the reaction wheel blades when it meets these blades to ensure gradual application of pressure to the blades. The oil has zero radial velocity as it passes over the edges 4|, 42, and then accelerates under the centrifugal action until it reaches the reaction wheel blades which then restrict and control its motion. The oil becomes confined within the peripheral pockets of the reaction Wheels and presses against them by its centrifugal force and moves outwardly of the casing along the other sides of the projections. At this period reaction from the oil is transmitted through the reaction wheel to the fixed reaction member 49 thereby producing the required increase of torque which is transmitted through the spindles 32, 33, casing 25, spindles 26, 35, and wheels 27, to the output shaft gear wheel 23. The oil applies reaction to the reaction wheel blades substantially only by the static pressure created by the centrifugal head of pressure arising from the difference in radii of the edges 4!, 42, and of the recesses 31, 38.

From the reaction wheels the oil passes over again into the driving wheels so that a continuous smooth band of comparatively slow moving oil exists around the inner wall of the casing 20. Energy not absorbed by the reaction wheels is returned to the driving wheels.

The gearing is so arranged as to obtain the required speed of the oil radially inwards on leaving the vaned driving wheels. During indirect drive, the fluid will move inwards for a short distance after leaving the driving wheels and then out again relative to the driven casing. The projections or dividing walls between adjacent recesses may be shaped to follow approximately the same curve as will be naturally taken by the oil leaving the driving wheels during infinite speed ratio, i. e., when the output shaft is stationary.

The speed of the driving wheels about their own axes becomes less as the speed of the output shaft approaches the speed of the input shaft and in direct gear the driving wheels cease to rotate about their axes. The driving wheels therefore supply a gradually decreasing quantity of oil to the reaction wheels as top gear is approached and when top gear is reached, the driving wheels and reaction wheels cease rotating about their own axes and no longer impel the oil from one to the other.

The torque output varies with transmission speed ratio and depends on the speed of the casing 28 so that for example with a given engine speed a fall of output speed results in increase in speed of the casing and consequential increase of torque.

Variation of the quantity of oil in the casing varies output torque without varying input speed and this effect can be utilised in various ways, e. g., for changing out of direct gear at difierent speeds. The engine or input full throttle curve can be varied in this way so that for example the engine can be controlled to work at maximum horse power speed or maximum torque speed or at required intermediate speeds.

The peripheral speeds of the driving and reaction wheels may be arranged to be approximately equal at infinite transmission speed ratio or preferably the peripheral speed of the reaction wheels will be slightly greater than that of the driving wheels to ensure filling the driving wheels pockets with oil.

The driving wheels deliver the oil at 4|, 42, at about the same speeds as they receive the oil having in the meantime imparted potential energy to it in the form of a centrifugal head of pressure.

An example of characteristics obtainable with this gear is illustrated by the full throttle curves in Figure 4, in which the ordinate represents output speed and the abscissa represents input (engine) speed. It can be seen that engine speed (curve A) can remain constant at a given speed (predetermined by design of the gear) until top gear is attained whereupon engine speed increases with increasing output speed. The curve B is speed of casing 28 which is faster than engine speed on starting and decreases as top gear is approached and when top gear is attained the casing rotates solidly with the input and output shafts.

The speeds of the reaction and driving rotors about their own axes are shown by curves C and D respectively (the abscissa then representing such speeds). These speeds decrease as top gear is approached and when top gear is reached, these speeds become zero and the rotors move solidly with the input and outputs shafts and the casing 28.

In Figure 5 the ordinates show output speed and the abscissae gives torque transmitted through the gear from an engine giving 60 ft./lbs. maximum torque. The torque curve shown in Figure 5 is made up of the torque transmitted by friction, gear reaction from the gear wheels, and the torque transmitted from the fluid. The torque curve can be varied by design of the gear, e. g., by varying the gear ratio between the input shaft and the casing 28.

Openings or grooves may be provided on the side walls of the casing at the ends of the wheels to enable air and fluid to change places in the spaces between the vanes and may enable the fluid to find correct balance if the amount of fluid taken up by the pockets is not uniform.

The casing may be emptied of oil for a disconnected or neutral condition.

According to the modification shown in Figure 6, the vanes or blades of the driving wheels and/or the reaction wheels are resilient. In the example shown, the blades 10 are mounted in slots radially (but the slots may be at an angle to the radial) in the wheels with springs H in the slots pressing the blades outwardly, stops not shown being provided to limit their outward movement. The blades thus engage the casing resiliently. This figure also illustrates that the blades may be drawn inwardly by projections on the blades engaging in cam grooves 12 in the side walls of the casing 28 so that the blades are out of the path of the fluid beyond the positions where the fluid is required to leave the driving whee-ls and travel towards the reaction wheels or where the fluid enters or leaves the reaction wheels. This avoids the possibility of the vanes beating against any fluid that may tend to accumulate at those positions.

The gearing together of the various parts may also be modified in several ways; for example, the input shaft may carry the spindles of pinions of an epicyclic gearing, the sunwheel of which is mounted on the output shaft and the outer toothed annulus of which is carried by the casing. A high speed of the casing or rotor is thus obtained on starting and an improved engine curve is obtained by this means. In another arrangement shown in Figure 7, the spindles 26, 30, of the driving wheels carry pinions gearing with a sunwheel 8| mounted on an extension 82 of the input shaft, which extension passes axially through the casing, the said spindles also carrying pinions 83 gearing with a sunwheel 84 carried by the output shaft.

Reverse drive may be afforded by various means, e. g., by an epicyclic gear instead of the lay-shaft type, or by gearing from the reaction sunwheel. One form of reversing gear is shown in Figure 8 and comprises pinions 81 on the spindles 26, 38 of the driving wheels gearing with a sunwheel 88 on a member 89 controlled by a. brake 98, pinions 9| also on the driving wheel spindles gearing with a sunwheel 92 carried by the output shaft 93. Application of the brake gives reverse drive. The gear sizes in this arrangement can be modified to give a fixed forward speed on braking instead of reverse. The brake may be replaced by a freewheel if a range from fixed low gear to 1:1 only is required.

The invention affords simplicity of construction and design. The gear is rotary in action and avoids complicated blading and difficult valves and provides for control by simple control of circulation of the fluid. Since the fluid does not move past the blades at high velocity, frictional losses are very low. The fluid flow is continuous and substantially uniform and all movement of fluid ceases in direct gear. The centrifugal action prevents mixing of air with the liquid and in fact instantaneously separates liquid from any air or other gas which may be present. The gear does not require to be full of liquid but contains only enough liquid to form the relatively thin band of liquid during operation.

Another advantage of the invention is that torque variation depends on velocity ratio between the input and output shafts (the geared up casing causing higher casing speed for greater velocity ratio thus producing more torque without increase in input speed) which is an advantage previously obtainable with the static type, e. g., swashplate gear, but obtainable only to a very limited extent with the kinetic type of gear. The torque value is, however, also dependent upon the input shaft speed, thus also obtaining the advantage of the known kinetic types of gears. Moreover, input torque can be transmitted directly through the mechanical connections, which has formerly been accomplished only in the static types of gears and not in kinetic types.

In the gear of the present invention also the power is not dependent on fluid velocity in relation to the blades and therefore frictional fluid loss is not dependent on the power transmitted.

Loads on the bearings due to centrifugal action may be high in some conditions but speeds are comparatively low and the loads are steady and are reduced rapidly with decrease in transmission ratio.

I claim:

1. An automatically variable torque converter comprising an input shaft, an output shaft, a rotary casing operatively connected to the input shaft and adapted to contain fluid which willbe impelled by the rotation of the casing centrifugally away from the axis of rotation of the casing, a rotary driving wheel within the casing having peripheral pockets and mounted on a spindle carried by the casing parallel to and offset from the axis of the casing and geared to the output shaft, a rotary reaction wheel within the casing having peripheral pockets and mounted on a spindle carried by the casing parallel to and offset from the axis of the casing, a fixed member on to which the reaction wheel is adapted to react, the casing having an inner curved surface surrounding the axis of the casing and shaped to form an inwardly directed projection of roughly V-cross-section having its apex projecting between the wheels but not far enough to reach the axis of the casing the surface of which projection on one side thereof closes the periph eral pockets in the driving wheel during its rotation and the surface on the other side closes the pockets in. the reaction wheel during its rotation, and means adapted to drive said driving wheel and reaction wheel in the directions in which the after t-e fluid will flow over the apex of the projection and into the pockets of the reaction wheel and will move outwardly along the other side of the projection and react on said reaction wheel also by centrifugal pressure, the arrangeinent being such that fluid entering the pockets of both wheels will flow substantially in the same direction as the direction of movement of the adjacent peripheral parts of the wheels and at approximately the same speed as said parts so as to act thereon substantially only by static pressure.

2. An automatically variable torque converter comprising an input shaft, an output shaft, a rotary casing operatively connected to the input shaft and adapted to contain fluid which will be impelled by the rotation of the casing centrifugally away from the axis of rotation of the casing, a rotary driving wheel within the casing having peripheral pockets and mounted on av spindle carried by the casing parallel to and offset from the axis of the casing and geared to the output shaft, a rotary reaction wheel within the casing having peripheral pockets and mounted on a spindle carried by the casing parallel to and offset from the axis of the casing, means adapted to drive the driving wheel and reaction wheel in such a manner that the driving wheel rotates at slower speed about its own axis as 1:1 ratio is approached so as to deliver less fluid to the reaction wheel and finally ceasing to rotate when 1:1 ratio is reached when no fluid is impelled by the driving wheel, and a fixed member on to which the reaction wheel is adapted to react, the casing having an inner curver surface surrounding the axis of the casing and shaped to form an inwardly directed projection Of roughly V-cross-section having its apex projecting between the wheels but not far enough to reach the axis of the casing the surface of which projection on one side thereof closes the peripheral pockets in the driving wheel during its rotation and the surface on the other side closes the pockets in the reaction wheel during its rotation, said means being adapted to drive said driving Wheel and reaction wheel in the directions in which the pockets in the driving wheel will receive fluid which will travel with the pockets and will be drawn thereby against the surface of the projection on one side thereof towards the axis of the casing whilst acting on the driving wheels by centrifugally developed fluid pressure Whereafter the fiuid will flow over the apex of the projection and into the pockets of the reaction wheel and will move outwardly along the other side of the projection and react on said reaction wheel also by centrifugal pressure, the arrangement being such that fluid entering the pockets of both wheels will flow substantially in the same direction as the direction of movement Of the adjacent peripheral parts of the wheels and at approximately the same speed as said parts so as to act thereon substantially only by static pressure.

3. An automatically variable torque converter comprising an input shaft, an output shaft, a rotary casing operatively connected to the input shaft and adapted to contain fluid which will be impelled by the rotation of the casing centrifugally away from the axis of rotation of the casing, a rotary driving wheel within the casing having peripheral pockets and mounted on a spindle carried by the casing parallel to and offset from the axis of the casing and geared to the output shaft, a rotary reaction wheel within the casing having peripheral pockets and mounted on a spindle carried by the casing parallel to and offset from the axis of the casing, a fixed member on to which the reaction wheel is adapted to react, a freewheel device arranged between the reaction wheel and the fixed part on which it reacts so that the reaction wheel ceases rotating on its own axis at 1:1 ratio, the casing having an inner curved surface surrounding the axis of the casing and shaped to form an inwardly directed projection of roughly V-crosssection having its apex projecting between the wheels but not far enough to reach the axis of the casing the surface of which projection on one side thereof closes the peripheral pockets in the driving wheel during its rotation and the surface on the other side closes the pockets in the reaction wheel during its rotation, and means adapted to drive said driving wheel and reaction wheel in the directions in which the pockets in the driving wheel will receive fluid which will travel with the pockets and will be drawn thereby against the surface of the projection on one side thereof towards the axis of the casing whilst acting on the driving wheels by centrifugally developed fluid pressure whereafter the fluid will flow over the apex of the projection and into the pockets of the reaction wheel and will move outwardly along the other side of the projection and react on said reaction wheel also by centrifugal pressure, the arrangement being such that fluid enterin the pockets of both wheels will flow substantially in the same direction as the direction of movement of the adjacent peripheral parts of the wheels and at approximately the same speed as said parts so as to act thereon substantially only by static pressure.

4. An automatically variable torque converter comprising an input shaft, an output shaft, a rotary casing operatively connected to the input shaft and adapted to contain fluid which will be impelled by the rotation of the casing centrifugally away from the axis of rotation of the casing, a rotary driving wheel within the casing having peripheral pockets and mounted on a spindle carried by the casing parallel to and offset from the axis of the casing and geared to the output shaft, a rotary reaction wheel within the casing having peripheral pockets and mounted on a spindle carried by the casing parallel to and offset from the axis of the casing, a fixed member on to which the reaction wheel is adapted to react, means to control the quantity of fluid in action so as to control torque output, the casing having an inner curved surface surrounding the axis of th casing and shaped to form an inwardly directed projection of roughly V-cross-section having it apex projecting between the wheels but not far enough to reach the axis of the casing the surface of which projection on one side thereof closes the peripheral pockets in the driving wheel during its rotation and the surface on the other side closes the pockets in the reaction wheel during its rotation, and means adapted to drive said driving wheel and reaction wheel in the directions in which the pockets in the driving wheel will receive fluid which will travel with the pockets and will be drawn thereby against the surface of the projection on one side thereof towards the axis of the casing whilst acting on the driving wheels by centrifugally developed fluid pressure whereafter the fluid will flow over the apex of the projection and into the pockets of the reaction wheel and will move outwardly along the other side of the projection and react on said reaction wheel also by centrifugal pressure, the arrangement being such that fluid entering the pockets of both wheels will flow substantially in the same direction as the direction of movement of the adjacent peripheral parts of the wheels and at approximately the same speed as said parts so as to act thereon substantially only by static pressure.

5. An automatically variable torque converter comprising an input shaft, an output shaft, a rotary casing adapted to contain fluid which will be impelled by the rotation of the casing centrifugally away from the axis of rotation of the casing, gearing between the input shaft and the rotary shaft, a rotary driving wheel within the casing having peripheral pockets and mounted on a spindle carried by the casing parallel to and offset from the axis of the casing and geared to the output shaft, a rotary reaction wheel within the casing having peripheral pockets and mounted on a spindle carried by the casing parallel to and offset from the axis of the casing, a fixed member on to which the reaction wheel is adapted to react, gearing between the reaction wheel and the fixed member, the casing having an inner curved surface surrounding th axis of the casing and shaped to form an inwardly directed projection of roughly V-cross-section having its apex projecting between the wheels but not far enough to reach the axis of the casing the surface of which projection on one side thereof closes the peripheral pockets in the driving wheel during its rotation and the surface on the other side closes the pockets in the reaction wheel during its rotation, and means adapted to drive said driving wheel and reaction wheel in the directions in which the pockets in the driving wheel will receive fluid which will travel with the pockets and will be drawn thereby against the surface of the projection on one side thereof towards the axis of the casing whilst acting on the driving wheels by centrifugally developed fluid pressure whereafter the fluid will flow over the apex of the projection and into the pockets of the reaction wheel and will move outwardly along the other side of the projection and react on said reaction wheel also by centrifugal pressure, said gearings being adapted to cause the speed of rotation of the casing to be a function of the difference in speeds of the input shaft and the output shaft, the arrangement being such that fluid entering the pockets of both wheels will flow substantially in the same direction as the direction of movement of the adjacent peripheral parts of the wheels and at approximately the same speed as said parts so as to act thereon substantially only by static pressure.

HOWARD FREDERICK HOBBS. 

